50mm x 47mm
It is important to realise, that agates displaying deformation banding in white appearing like "bubbles" or "froth" such as one would see in a glass of lager beer, predominantly also in grey-blue colours (although this is not always the case) are not ONLY found in the vicinity of Barras Quarry. Fine agates of this sort are encountered at Barras often, it is true, but agates indistinguishable from the Barras variety save their water-washed nature as also in my experience to be found at every beach locality south (and adjacent) to the aforementioned locality.
Anyway, here is an unusually large example found by myself during the late summer of 2015. It's interesting to see how the fortification agate in the upper portion of the stone (as a newly cut imago the central banding in white was far more defined, drying has created "clouding") never REALLY becomes water-level or onyx banding. It considers weathering the process, but declines even as it grows flatter and in resistance appears to become unmarked chalcedony showing disgruntled areas of fractured seawater corrosion. Or something.